Power converters are often used to convert power from one form to another. These power converters typically have maximum power ratings. However, in some applications, the power to be processed is greater than that which can be handled by a power converter.
One way to solve this problem is to simply build a power converter that can handle more power. However, this can be technically difficult, and depending on the demand for such converters, it can be poor business practice.
Another way to realize a power converter with high power rating is to connect multiple lower-rated power converters in parallel. For the lower-rated converters to co-operate in achieving a higher power rating, the switching operation of switching devices (typically insulated gate bipolar transistors) is coordinated at nearly all times. In particular, the switching operation is controlled so that outputs of each of the lower-rated power converters are maintained in phase relative to each other.
In some cases, power converters communicate amongst themselves on two channels: a first channel for transmission of a synchronization signal, and a second channel, such a as a CAN serial bus, for exchange of control data. In this configuration, a master power converter broadcasts a pulse periodically for a slave power converter to use as a reference for a phase locked loop, along with data exchange of commands for control execution.
In other instances, Industrial Ethernet protocols incorporate synchronization and data exchange onto the Ethernet physical layer (e.g., Cat 5 cable and related connectors). For instance, Powerlink, Sercos III, and EtherCAT may be used for coordination of soft paralleled power converters. Beyond this configuration, a custom protocol may be built on top of a conventional Ethernet hardware layer.